Sample Chat Application

Objective:

Implementing a chat application that will populate at startup 200 users in the database and echo back any message sent after a delay of about 500ms.

github.aeharake.choters

This package contains the root Application which is ApplicationController In the ApplicationController we initialize Fresco library that will be used in the entire application

github.aeharake.choters.mocker This includes whatever we would like to mock, we have one class for mocking the 200 users which is: UsersGenerator

github.aeharake.choters.activities

This package contains all the activities. We have two activities:

1. MainActivity

This activity is responsible or showing us the users and their last message

2. ConversationActivity

This activity is responsible for showing us the Conversation between user and his contact.

  github.aeharake.choters.adapters

This package contains all the adapters, we have two adapters:

1. UsersAdapter This will bind the data to User row in the main activity

  2. ConversationAdapter This will bind the message received/sent in the ConversationActivity to item_row_friend or item_row_me. This is decided from inside the adapter in getViewType()

github.aeharake.choters.repos

this package contains all the project repositories. The BaseRepository is the parent of all repositories holding reference to the database and the data access object. We have two repositories in the app:

1. UsersRepository

This contains the logic behind:

• Checking whether the user’s table is empty or not. If it’s empty then UsersGenerator class will be used to generate for us the 200 full names, once we have them we will be creating from this repository our User entity and insert them in bulk using our UsersDao
• Getting the users as LiveData so that the MainActivity can observe on users changes.

2. MessageRepository:

Responsible for:

• Inserting the sent message and the message that should be “echoed” after a certain delay
• Getting the messages as live data so that whenever there is a change in the database the recycler-view’s adapter should be notified from ConversationActivity.

github.aeharake.choters.room This package contains all what is related to room database, including entities and DAO interfaces

- github.aeharake.choters.room.dao

1. DAO

• BaseDao.kt (parent interface of all DAO objects) This was added to be able to pass it as non-null generic type
• UserDao.kt Responsible for the query to get the users and insert the users
• MessageDao.kt Responsible for the queries of getting the messages between two persons and inserting the messages as well.

- github.aeharake.choters.room.entities

2. Entities

• Message.kt This entity has two foreign keys to the User entity, to specify the sender and the receiver
• User.kt This holds the user information
• UserMessage.kt This will holder the user + last message sent/received
• ChatDatabase.kt: Responsible for creating the database if it does not exist. Only one instance of ChatDatabase will be alive during the application lifecycle

github.aeharake.choters.viewmodels includes all the view-models of the application

1. UsersViewModel This will talk with the UsersRepository

Methods involved:

fun getAllUsers(): LiveData<List<UserMessage>>

fun populate()

2. ConversationsViewModel This will task with the MessageRepository:

• Methods involved:

fun getAllMessages(id: Int): LiveData<List<Message>>

fun insertMessageAndEcho(text: String, id: Int)

  github.aeharake.choters.ui This package contains the custom view which is SendTextView

github.aeharake.choters.utils Includes the helper classes:

1. CalendarHelper This class will get us the time in pretty format.

2. CodeUtils Also, a helper class that holds some code that can be used a lot in the project to avoid code repetition.